For testing purpose, I just try to sleep with my watch (42mm Black link), very comfortable. I have a 150mm wrist, and remove 7 links in total makes the band perfectly fit on my wrist.
More sharing, I leave the silent mode always on, and realise that the tapic engine can actually wake me up easily. I never feel that the tapic engine is strong, it's just good enough to catch my attention for notifications in day time (Prominent Haptic ON). However, during sleep, I realise that my wrist is actually more sensitive to this kind of vibration. It's a more effective way to wake me up than a normal alarm, and it won't alert my baby as well. Much better than I expect.
In terms of battery usage. I charge the watch to 100%, and then go for sleep, wake up at 85%. Since I am not interest in the activity tracking, so I turn everything off in that app, also power saving mode ON in Workout app (but the heart rate monitoring functions still on). All other normal functions still on, strongest haptic strength, stock brightness setting. The watch still have >50% battery after 10 hours use (including receive few quick phone calls, around a hundred of messages / notifications in total, and around 1hr of playing around). So, it's definitely not an issue at all.
